In a variety of types of aircraft, air-breathing propulsion systems such as turbojet or turbofan engines are used for propelling the aircraft at supersonic velocities. Existing commercially available gas turbine engines used for aircraft propulsion are generally designed to work where subsonic flow, typically on the order of Mach 0.3 to 0.6, exists at the inlet side of the engine. Therefore, a supersonic engine inlet must decelerate the intake supersonic air stream to a subsonic speed for input to the engine. The process of deceleration is technically known as diffusion or compression, since the excess kinetic energy of the air stream is converted into a static pressure increase. To accomplish this, the inlet must subject the air to a shock system where losses in total pressure occur that reduce the net thrust and net thermal efficiency of the engine. Inlets are typically designed to place a final terminal shock from supersonic to subsonic flow.
Supersonic aircraft engine air inlet designs must operate efficiently over a broad range of conditions from very low speeds for takeoff to very high speed cruise. A critical challenge for the successful design of supersonic aircraft is air inlet systems which can operate at low speed and high thrust conditions for takeoff and in flight conditions ranging from subsonic to transonic, and supersonic regimes. Supersonic inlets need to accommodate changing requirements with airspeed. Typically inlets incorporate a forward ramp or spike surface ahead of the enclosed portion of the inlet which presents an angle to the flow to generate a weak shock system to slow and compress the air before entering the enclosed portion of the inlet. The ideal ramp angle for such an inlet changes with Mach number. As Mach number increases, the engine will accept less air than provided by the inlet system, and the excess must be either spilled around the inlet or bypassed through auxiliary openings in the inlet internal and external surfaces.
To accomplish changing the intake airspeed at different aircraft operating speeds, typically supersonic aircraft have incorporated complex and heavy variable ramp and bypass systems to accommodate these supersonic matching problems. Improvements are needed to provide lighter, more efficient and less complex means for accommodating the diverse requirements of supersonic aircraft inlets by providing a simplified actuation mechanism that reduces overall weight and space requirements. It is with respect to these and other considerations that the disclosure herein is presented.